After a cold and wet washout spring, with the soggiest April on record and a chilly May following a freakishly warm March, most of the country is in the mood for some sunshine. But not the government officials in charge of the drought response – they are hoping for a "cool, damp summer", because any sort of heatwave could plunge us back into severe water shortages and wreak havoc for the Olympics.

Record rainfall in April pulled south-western, some northern and Midland counties out of the drought – but that will not last for long if temperatures rise, because groundwater levels in many parts of the country are still stuck at their lowest levels in a century, officials warned.

They were speaking ahead of a meeting of the agencies responsible for tackling the shortages after two dry winters that have depleted aquifers and rivers.

"The best scenario would be a cool damp summer," said Trevor Bishop, head of water resources at the Environment Agency. He pointed out that the factor that made the 1976 drought so severe was that two dry winters were followed by a scorching summer, which dried out soils and water sources but also put more demand on what stocks there were, as farmers, businesses and households sought to cope with the effects of the heat.

Recent rains have taken the immediate pressure off the drought that in March stretched across most of England, with some groundwater sources in chalk areas recharging particularly quickly. "We were surprised by the amount of recharge – but then we'd never seen the wettest April on record," said Bishop.

However, the picture is very varied across the country. In areas where the bedrock is sandstone it may take months longer to recharge. It is not possible to judge the state of groundwater across England on aggregate, but in some areas it is still at record lows, based on data stretching back about a century.

River flows are also up, but this does not necessarily relieve the drought because water companies in the south tend to take most of their water from aquifers rather than rivers and reservoirs.

"The very intense rainfall we've had was masking the symptoms of the drought, not dealing with the cause," which was a lack of winter rain recharging underground sources, said Bishop.

Because of the lack of vegetation, winter rain reaches the ground quickly, but in summer growing plants and warmer temperatures that lead to higher evaporation means the rain does less to replenish deep sources. Hard and dry, compacted soils also tend to be less good at soaking up rainfall, which can run off or cause flash floods.

Bishop said: "What really worries us is the future – we have to plan 25 years ahead." The Environment Agency is already planning for a drought that lasts three, four or even five winters, and is working with water companies, electrical utilities, farmers and industry to try to make the UK's water infrastructure more resilient.

"In the 20th century, we have not seen a drought that has extended more than two winters," said Vicky Pope, the drought coordinator for the Met Office. "But it's very important not to just base decisions on recent experiences."

This June may be warmer than average, according to the latest tentative forecast, but the Met Office is not issuing any clearer guidance for the summer. Stung by criticism of its 2009 forecast of a "barbecue summer" that ended up seeing grey, overcast skies – though temperatures were above average, as predicted – the agency has stopped publicly releasing medium-term forecasts.

A key question is whether the current run of dry winters and wetter summers is part of a broader pattern. Pope said that several factors were playing a part – including the North Atlantic Oscillation, a long-term weather pattern observed from Iceland to the Azores that in its positive phase brings westerly winds and stormy wet weather to the UK, with warmer winters.

In its current negative phase, however, the oscillation can bring colder, drier winters – which come as a surprise to most of us because they followed a long positive phase, but which are part of the natural variation of the UK's climate.

Another factor is the El Niño weather system in the Pacific, whose effects can extend as far as the UK, and the solar cycle, which is currently at an unusually low phase, which historically is associated with colder winters in Europe.

But one big unknown is the effect of the loss of sea ice in the Arctic – in the last 30 years, an area the size of Greenland has been lost from the ice cap, and this is likely to have a significant effect on Europe's climate, according to recent research, including potentially colder winters. However, it is too early to say for definite.

The Met Office has a major programme of work under way with its newly refurbished supercomputer, trying to establish whether the recent changes could be the result of climate change, and how they are likely to develop in future. It could be several years before the results are known, however.